In occupations or activities which occur under extreme environmental conditions, such as high heat and/or humidity, it is often necessary to monitor the environment to determine if working conditions are safe. The environmental parameters which are typically measured are dry bulb, wet bulb, and black globe temperature. From these three parameters, the wet bulb globe temperature (WBGT) index can be calculated. The WBGT index is an industry standard metric for assessing susceptibility to heat strain. There are a number of commercially available devices which calculate the WBGT index, and some devices suggest a maximum safe work time based on this result.
In the field of environmental monitoring it is desirable to have a portable measurement device so that measurements can easily be taken in different locations. Previous monitoring devices have sensors that are mounted to a tripod and attached to a separate display unit by a cable. This can limit their use to areas which can physically accommodate such equipment. Other devices use individual sensors which directly attach to the display unit, and are removed and placed in a protective case for storage.